Animal movement decisions and associated energy expenditure have important implications for survival and fitness, which in turn scale up to shape broader population dynamics. In coastal marine ecosystems, environmental conditions that promote resource availability are highly dynamic, necessitating the ability of foraging individuals to continually modify their behaviors over time. However, due to environmental disturbances, particularly those borne of anthropogenic processes, animals are often diverted from their normal activities, resulting in reduced efficiency of movement and potential fitness impacts. Modern tracking technologies have allowed remarkable insights into the foraging behaviors of animal populations, but often lack an important component of variation: that within the individual. Understanding which individuals modify their behaviors in response to changing conditions, how do they do so, and their consequences are necessary to further understand both the ecological effects of environmental disturbance and the mechanisms by which individual specializations may arise within populations. In the northern Gulf of Mexico, brown pelicans (Pelecanus occidentalis) navigate a foraging landscape that is patchy and dynamic at a variety of scales due to both natural and anthropogenic stressors. From 2012-2017, we have attached GPS transmitters and accelerometers to breeding adult pelicans on Raccoon Island, the largest colony in coastal Louisiana.
Results/Conclusions
We observed increases in foraging site fidelity in tracked pelicans as the breeding season progresses, but lower fidelity and less variation in energy expenditure in birds of higher body condition. That high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand is consistent with a 'rich get richer' scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. Additionally, assessments of traditional foraging metrics such as trip distance, linearity, or duration have not yielded significant relationships among individuals, highlighting the importance of considering variation at multiple levels in attempts to characterize foraging strategies in wild populations. Upcoming work will combine these findings with additional accelerometer analysis, ecotoxicological assays, and expansion to additional colonies to understand the relative contributions of foraging energetics, environmental cues, contaminant exposure, and restoration activities to population-level processes in heavily disturbed systems such as the northern Gulf. These and future results will provide unprecedented insights into the movement ecology and demography of an important seabird, which will provide valuable information to basic behavioral ecologists as well as barrier island restoration efforts currently underway throughout the Gulf coast.